Elec 04-01 to Elec 04-04 AC Circuits

In a parallel ac circuit with XL and XC

• IL and Ic are 90° out of phase
• IL and IC are in phase
• IL and IC are 180° out of phase
• XL and XC are 90° out of phase

What is the term for the out-of-phase power associated with inductors and capacitors?

• Effective power
• True power
• Peak envelope power
• Reactive power

In an AC circuit, if the voltage and current are in phase, the circuit is

• resistive
• capacitive
• reactive
• inductive

For a capacitor in a sine-wave ac circuit

• Vc lags ic by 90°
• ic leads Vc by 90°
• ic and Vc have the same frequency.
• All of the above

In a parallel RL circuit

• IL lags IR by 90°
• IL leads IR by 90
• IL and IR are in phase
• IR lags IL by 90°

What is the power factor (PF) of a purely resistive ac circuit?

• Zero
• 1
• 0.707
• Without values, it cannot be determined

A resistive and a capacitive load of equal magnitude is connected in series, determine the phase difference between the voltage and the current

• current leads the voltage by 45°
• current lags the voltage by 45°
• current leads the voltage by 90°
• current lags the voltage by 90°

For an inductor in a sine-wave ac circuit,

• VL leads iL by 90°
• VL lags iL by 90°
• VL and iL are in phase
• None of the above

What will happen when the power factor of a circuit is increased?

• Reactive power increases
• Active power increases
• Both active and reactive powers increases
• Both active and reactive powers decreases

The impedance in the study of electronics is represented by resistance and ________.

• inductance and capacitance
• inductance
• reactance
• capacitance